1. Field of the Invention
The present invention relates to a reverse transcriptase inhibitor and an antiviral agent, and more specifically the present invention relates to a reverse transcriptase inhibitor and an antiviral agent which comprises sulfated tyrosines and/or physiologically acceptable salts thereof as an effective component.
2. Description of the Prior Art
AZT (azidothymidine: a reverse transcriptase inhibitor), which is the first agent for the treatment of AIDS (Aquired Immune Deficiency Syndrome), has been found to significantly delay onset and progress of AIDS. However, AZT has some problems such as a chronic toxicity caused by a long-term administration thereof and an appearance of a drug tolerance mutant of AIDS viruses. Although a therapy using AZT in combination with DDI (dideoxyinosine) was recently approved, there have been also reported grave side-effects, such as an acute pancreatitis. Both AZT and DDI are mononucleotides and affect not only a reverse transcriptase but also a human polymerase, and it follows that they lack selectivity.
A Japanese Unexamined Patent Publication (J.P. KOKAI) No. Hei 2-178232 discloses a pharmaceutical composition comprising a poly (amino acid) sulfonate as an effective component for the treatment and prevention of retrovirus infections, in particular AIDS. However the effective component is a polymeric compound having a molecular weight of from about 500 to about 500,000 dalton and therefore such compound can not be handled easily and the structure thereof, for example, a degree of sulfonation in the molecule is not specified.
There are now some antiviral agents under investigation, such as a protease inhibitor, a transcription and translation inhibitor, an uncoating inhibitor and an inhibitor against glycoration of an envelope protein of HIV.